Tire building form having coaxial discs

ABSTRACT

A method of manufacture of a tire in which a carcass ply is formed by winding a continuous cord around a pair of spaced members to form a ply (31) having loops (36) at its edges. The cord ply is rubberized and support elements (32)(33) are located in the loops (36) to form a cylindrical ply having spaced hooped support elements at each ply edge. Bead wire assemblies (40) and (41) are located coaxially of the ply together with the support elements which are subsequently incorporated in the bead wire assemblies. 
     There is also provided a tire building former on which the above method can be performed. The former (100) comprises at least three coaxial discs (101), (102), (106) for supporting a carcass ply 30 on their radially outer surfaces. The central disc (106) is axially movable between the two other discs so as to support a portion of an elastomeric ply (103) helically wound onto the former (100) from a strip (1040.)

This is a Divisional of application Ser. No. 214,842 filed Jun. 30,1988, now U.S. Pat. No. 4,929,292, which in turn is a continuation ofapplication Ser. No. 891,113 filed Jul. 31, 1986, now abandoned.

This invention relates to methods and apparatus for the manufacture ofpneumatic tire(s).

In the conventional manufacture of radial carcass pneumatic tire(s) aply of parallel rubberized tyre cords is laid on a drum or former withthe cords extending axially of the cylindrical former, over an innerliner, and the bead wire assemblies are placed in axially spacedpositions coaxially around the ply, following which the ply is expandedinto engagement with the bead wire assemblies and the axially outerportions of the ply are turned around the bead wire assemblies toprovide ply "turn ups" which in the shaped and finished tire(s) mayextend for a considerable distance radially outwardly from the bead wireassemblies.

One object of the present invention is to provide a method ofmanufacture of a tyre and apparatus therefore in which the bead "turnup" can be substantially reduced.

The invention is particularly suitable for use in the manufacture of atire(s) having a carcass ply produced by a method and apparatus asdescribed in GB 2159185A and its U.S. equivalent U.S. Pat. No.4,602,973.

According to the invention there is provided a method of manufacture ofa pneumatic tire(s) including winding a cord reinforcement around a pairof spaced members to form a ply of continuous reinforcement cord havinga series of loops adjacent the edges of the ply, rubberizing the cordsto form a reinforced elastomeric ply, locating at least one supportelement in the loops at each edge of the ply to form hooped supportelements at each ply edge and shaping the ply into a cylindrical form,locating a bead wire assembly coaxially of the cylindrical ply togetherwith the support elements and incorporating the support elements in eachrespective bead wire assembly to anchor the loops of cord to eachrespective bead assembly.

The support elements may be wires which are formed into rings the endsof which may or may not be joined together. The support elements may beformed as an integral portion of the bead wire which is passed throughthe loops on each side of the ply and is then hooped and forms part ofthe bead assembly which comprises bundled wire hoops.

Alternatively when built into a tire(s) the support elements may becircled and welded and fitted against the bead wire assemblies so as toanchor the loops of cord securely. Each bead wire assembly may bepre-formed with a notch suitably positioned to receive the associatessupport wire.

The invention further provides a tire(s) building former comprising aseries of rotatable discs for supporting a tire(s) carcass on theirouter surfaces, at least one disc being arranged to support part of atire(s) inner liner formed as a winding thereon and to travel during thewinding process from a position at one end of the former to a positionat the other end of the former.

Embodiments of the invention will now be described, with reference tothe accompanying drawings, in which:

FIG. 1 is a diagrammatic view of a carcass ply and support elements asutilized in the present invention also showing an enlarged detail,

FIG. 1A is an enlarged portion of FIG. 1;

FIG. 2 is an alternative carcass ply and bead assemblies which may alsobe utilised in the present invention also showing an enlarged detail,

FIG. 2A is an enlarged portion of FIG. 2.

FIGS. 3 to 11 are diagrammatic axial cross-sectional views showingstages in the manufacture of a pneumatic tire(s) carcass and itsincorporation into a tire(s) tread assembly;

FIG. 12 is a diagrammatic axial end view showing in more detail thestage illustrated in FIG. 7, and

FIG. 13 is an axial view at the same stage;

FIGS. 14 to 20 are similar views to those of FIGS. 1 to 9, showing analternative process, and showing details of the former in cross-sectiononly above the centreline of the former;

FIGS. 21 to 23 show in more detail the former illustrated in FIGS. 14 to20, and

FIG. 24 shows an alternative step using the carcass ply of FIG. 2.

FIG. 24A is an enlarged portion of FIG. 24.

With reference to FIGS. 3 to 11, the sequence of steps in themanufacture of a pneumatic tire(s) is as follows:

FIGS. 3 to 5 illustrate a method for the preparation of a rubber innerliner 27 for the tire(s) from a narrow strip 10 which may be fed from astock roll, or preferably from a small calender, adjacent to a tire(s)building former 11 which comprises a series of coaxial, axially movablediscs 15, 16, 17, 18 and 19. The discs 15 to 19 each have a cylindricalouter surface for supporting the tire(s) carcass or part of the tire(s)carcass at various stages of its manufacture. The former 11 has adiameter larger than the bead diameter of the tire(s) to be builtthereon.

As shown in FIG. 3 the inner liner 27 is in process of formation bywinding the strip 10 as a continuous helical axially extending winding,initially on the rotating discs 15, 17 and 19, which are groupedtogether at one end of the former 11, and a pressing roller 25 is usedto lay the strip on the discs and the winding processes by axialmovement of the roller 25 from left to right to form a continuousbutt-or scarf-jointed layer. Normally, two layers of the strip 10 arewound with the joints of the second layer staggered relative to thejoints of the first layer.

FIG. 4 shows the completion of the winding to form the inner liner 27.Since the winding is laid helically it will be necessary for the ends tobe trimmed (this step is not shown) and the discs 15 and 16 are thenremoved axially leaving the liner 27 supported on discs 17, 19 and 18 asillustrated in FIG. 4. It will be noted that the discs 17 and 18 remainaxially stationary and that the disc 19 travels, during the windingprocess, from the position adjacent disc 17 shown in FIG. 3 to theposition shown adjacent the disc 18 in full lines in FIG. 4 at theopposite end of the former. The disc 19 moves axially to remain inalignment with the strip so as to support the strip as it is woundacross the former. This enables a hollow former to be employed, and thusto allow all the tire(s) building operations including shaping to becarried out on the same former. After the winding of the inner liner thedisc 19 returns to the position shown in dotted lines in FIG. 4 in thecentral region of the former.

FIG. 5 shows the end portions 28, 29 of the liner turned down (radiallyinwardly) against the end surfaces of the discs 17 and 18. The innerliner is now in a suitable condition to receive a carcass reinforcementply 30 as illustrated in FIG. 6.

The ply 30 is conveniently manufactured by apparatus similar to thatdisclosed in published patent application GB2159185A (U.S. Pat. No.4,-602,973) which comprises a pair of longitudinally extending rotatablespindles mounted in spaced apart parallel relationship one for each edgeof the ply fabric, a cord winding head, and means for rotating thewinding head around the pair of spindles so as to form a winding of cordwhich passes around both spindles and is progressively moved axiallyalong the spindles by helical members coaxial with the spindles androtating in opposite directions to the direction of spindle rotation tomove the winding in sychronization along both spindles.

The cord ply formed on the above apparatus comprises continuous cordreinforcement 31 having a series of loops 36 adjacent the edges of theply. This is illustrated in FIG. 1.

The preparation of the ply further comprises the step of applying thinsheets of unvulcanized rubber to the upper and lower surfaces of thecord winding as it emerges from the spindles thus producing a rubberizedparallel-cord ply in which the edges having un-rubbered loops of cordprotruding from the edges of the rubberized fabric.

Support elements, 32 and 33 preferably wire elements, but it isenvisaged that other materials such as aromatic polyamides, nylons, orpolyesters could be used, are located through the loops 36 at each edgeof the ply subsequently to form hooped support elements at each edge ofthe ply when it is formed into a cylindrical shape.

The support element may be located into the loops after the cord ply hasbeen rubberized or alternatively may be located into the loops prior tocords being rubberized.

One method of incorporating the wires into the loops is to pass eachsupport element wire through the centre of a respective spindle so thatthe loops of cord are held on the support elements as they are removedfrom the spindle.

the above method may produce a continuous length of reinforcedelastomeric ply which is then necessary to cut to suitable ply lengthsas required. If the support elements are already in place it will benecessary to sever both the reinforcement cord and the support wires.The ply and support elements are formed in a cylindrical shape withhooped support elements at each end.

A ply 30 as shown in FIG. 6 thus comprises a cylindrical layer ofrubberized cord material 31 in which the cords lie in the axial,direction and have loops 35 passing around support wires 32, 33. Afterforming the support wires to circular form around the former their endsare welded (adjacent cord loops being parted to enable weldingelectrodes to be inserted without damaging the fabric) and the circledsupport wires are then crimped so as to enable the ends 34 and 35 of theply to be turned radially down the ends of the former as shown in FIG.7. The formation of the support wire 32 in its crimped state is shown inmore detail in FIG. 12, which also shows the position of the weld 38 bywhich the ends of the wire 32 are secured together and which indicates abead wire assembly 40 which is then brought into position adjacent thecorresponding end of the former as shown in FIG. 8. A similar bead wireassembly 41 is placed at the opposite end of the former. The bead wireassembly preferably comprises a plurality of hooped turns of continuouswire bundled together into a suitable bead shape, for example, square,hexagonal, circular, etc. The bead assemblies 40 and 41 are formed witha turn of wire left out of the axially outer side of the bead bundle inthe radially outer layer of wire so that there is a vacant position inthe bead wire configuration in the outer layer of the bead assembly.

Apparatus for forming the support wires 32, 33 to the crimped conditionshown in FIGS. 7, 8, 12 and 13 is not illustrated but may take the formof a series of coaxially extending fingers arranged initially around twopitch circles of different diameters and moved axially towards theformer, respectively, radially within the radially outside the wire 32or 33. The fingers are then contracted, the outer fingers being drawnradially inwardly to a greater extent than the inner fingers so as todeform the support wire as shown in FIG. 12. This effectively reducesthe diameters of the support wires to enable the bead wire assemblies 40and 41 to be fitted against the turned-down portions 34, 35 of the plyas seen in FIG. 8.

The axially extending fingers are then withdrawn axially outwardly andreleased to permit the support wires 32, 33 to resume their naturalcircular configuration.

FIG. 9 shows the condition of the partly-built tire(s) carcass followingrelease of the support wires. A further operation, shown in FIG. 10, isthen employed to press the support wires into engagement in the suitableannular notches 43, 44 or spaces, which have previously been formed inthe bead wire assembly configuration, as previously described.

The completed ply, liner, and bead assemblies are consolidated as shownin FIG. 10 and the ply is tensioned by moving the discs 17 and 18slightly away from one another. Other tire(s) components such as apexes,chaffer strips, etc., may be added at this stage.

Th next stage is a shaping operation as illustrated in FIG. 11, in whichthe interior of the tire(s) is inflated by suitable conventional meansand the discs 17 and 18 moved towards one another, thus shaping thetire(s) carcass to toroidal form. Conveniently the shaping operation iscarried out within a tread carrier ring 50 in which a previously mouldedtread and breaker assembly 51 is positioned around the carcass so thatthe breaker and tread are assembled accurately with the breaker andtread in symmetrical relationship to the circumferential centre line ofthe carcass. The tread carrier ring 50 may constitute a mould, and thesidewalls may be added in pre-moulded condition, carried on suitablesidewall moulding plates, to enable the final curing operation to becarried out as described in our U.K. Application No. 2134439A.

FIGS. 14 to 20 show a second method also of manufacturing a pneumatictire(s) in accordance with the invention, and which also illustrates aformer in greater detail.

FIG. 14 shows a winding process in which a liner is built by aprogressive helical winding of a strip around a former as previouslydescribed with reference to FIGS. 1 to 9. The building former assembly100 comprises three rotatable discs 101, 102, and 106 and its operationis generally similar to that described above in relation to FIGS. 3 and5 except that only three discs are used. The winding commencing on apair of discs 101 and 102 of which the disc 102 is moved to the right,supporting the liner 103 as it is wound under a moving roller 104, andthe winding terminates on a disc 106. The three coaxial discs 101, 102,106 are mounted on a hollow shaft 130 and are axially moveable byinternal rods 131 and 132. The rod 131 having oppositely handed screwthreaded portions thereon for movement of the discs 101 and 106 towardsor away from each other in a known manner.

FIG. 16 shows the addition of the carcass reinforcement ply 30 (omittedfrom the lower part of the drawing) in which the portions containingsupport wire elements 108, 109 project beyond the edge of the formerassembly, and in this example the overall diameter of the former, liner103, and ply 30 is arranged to be slightly less than the internaldiameter of bead wire assemblies 115, 116 (see FIG. 17) which are to bebuilt into the tire(s) carcass. It will be noted that the support wires108, 109 may be formed as a broken ring in which the ends of the wirelength are not welded together but have a short overlap to enable thecircled support wires to be expanded in diameter, before welding, to thefinal diameter required to fit in the required position against the beadwire assembly.

FIG. 17 shows the bead wire assemblies 115 and 116 placed in positionover the linear and ply on the former 100 and FIG. 18 shows theexpansion of discs 101 and 106 to grip the bead wire assemblies 115,116, through the ply. The disc 101 and 106 include radially slidablesegments 136 and 137, having inclined cam surfaces 138 on the radiallyinner end portions thereof which are engagable on a conical disc 140slidably mounted on the shaft 130. The support wires 108, 109 areexpanded to their required diameter i.e. with their ends abutting. Theends of the wires 108, 109 may be then welded together to forminextensible rings which as shown in FIG. 19 are then pressed by asuitable device into engagement with corresponding notches 118, 119formed, respectively, in the bead wire assemblies 115, 116 (aspreviously described). As before apex strips and chaffer strips may beadded at this stage. The ply is then tensioned by outward movement ofthe disc 101, 106. The carcass is then shaped into engagement with atread and breaker package 125 carried in a tread moulding ring 126 asshown in FIG. 20. Finally, premoulded sidewalls carried on suitablesidewall moulding plates are added and whole assembly is cured asdescribed in our U.K. Application No. 2134439a.

FIGS. 21, 22 and 23 show in more detail the sequence of operations toexpand the disc 101 so as to bring the ply 30 and a double thicknessliner 103 into engagement with a bead wire assembly 115. The former 100incorporates a sleeve 120 of flexible plastics material extending fromone end of the former to the other and supported on the radiallyexpansible segments 136 and 137. The purpose of the sleeve 120, when theoperation of FIGS. 14 and 15 is being carried out, is to support theliner 103 while permitting the traveling disc 102 which is maintained inalignment with the roller 104, to move within the sleeve 120 across theaxial width of the former between the discs 101 and 106. The sleeve 120is of low-friction material to enable the disc 102 to slide freelywithin it, and acts to counter any tendency which the axial movement ofthe disc 102 might otherwise have to pull the windings apart as it movesacross.

FIG. 22 shows the disc 101 and the segments 136, and 137 expanded togrip and position the bead assembly 115, the expansion of the segments137 providing a shoulder for accurate location of the bead wireassembly.

In FIG. 23 the shaping of the tire(s) carcass with apex strips 122 nowadded is illustrated, and in this operation the central portion of thesleeve 120 is deflected radially inwardly by the inflation pressure,which it serves to retain by sealing the inner parts of the former.

With reference to FIG. 2 and FIG. 24, in an alternative method thesupport elements may be formed as a single hoop of wire which is aportion of the continuous wire of the bead wire assemblies. Each bead215 is formed of a plurality of turns of a wire, a portion of this wiremay be located in the loops 36 at the respective edge of the ply 30 sothat support members 232 and 233 for the loops are actually constitutedby a single turn of the bead assembly 215.

Thus, in FIG. 24, the bead assemblies 215 are formed simultaneously asthe ply 30 is wound onto the former 100. The operation of the former 100continues as before.

We claim:
 1. A substantially cylindrical tire building former comprisingat least three rotatable coaxial discs for supporting a tire carcasselastomeric ply at their radially outer surfaces, two of said discsbeing end discs with one end disc being associated with each axial endportion of the former, a flexible sleeve extending between said enddiscs, and the other inner disc being arranged to move within saidsleeve between the two end portions of the former so as to support aportion of an element ply to be helically wound onto the former from astrip; said two end discs being capable of simultaneous movement towardsand away from each other, and each said end disc having two sets ofradially expandable segments for pressing a carcass ply against a beadassembly located around the ply, the axially inner ste of segmentsproviding a shoulder for location of a tire bead and the axially outerset of segments being expandable to press against the internal surfaceof said tire bead.
 2. A tire building former as claimed in claim 1,wherein the three discs are mounted on a hollow shaft, and are axiallymoveable thereon by rods located within the shaft, the two axially outerdiscs being connected to oppositely handed screw threaded portions ofone rod for movement towards and away from each other, and the innerdisc being connected to a second rod for movement between the twoaxially outer discs.
 3. A tire building former as claimed in claim 2wherein the radially expandable segments each have radially inner endportions with an inclined cam surface thereon which is engageable with aconical disc slideably mounted on said shaft.
 4. A tire building formeras claimed in claim 1, wherein the former comprises five coaxial discs,there being two discs associated with each axial end portion of theformer, the axially outer disc of the two discs on an end being axiallyremovable to leave any ply on the former supported only on the threeaxially inner discs.
 5. A tire building former as claimed in claim 1,wherein said sleeve provides a support surface for the elastomeric stripwhich is wound thereon, and the sleeve further serves to seal the innerparts of the former when the end discs are moved together and a carcassply on said sleeve is shaped into a toroidal form by inflation pressure.